Safety-fuse.



G. W. HART @E F. D.. REYNOLDS.

Ptentea Mar.' 2, 1909.

A SAFETY Pusjs. APPLICATION FILED JULY 28, 1906.

thereof, whether or, 'not the`fuse UNITED sTATEs PATENT oEEroE.

GERALD W. HART AND FRANK D. REYNOLDS, OFIHARTFORD, CONNECTICUT, ASSIGNORS TO THE SACHS COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CON- NECTICUT.

SAFETY-FUSE l Specification of Letters Patent.

Patented March 2, 1909.

To all whom it may concern:

Be it known that we,'GERALD W. HART and FRANK D. REYNoLDs,both citizens of the United States, residing at Hartford, in the. county of'I-Iartford and State of Connecticut, have invented an Improvement in Safety-Fuses, of which the following is a specification..

Ourinvention relates to safety fuses and articularly to that class of inclosed safety uses which heretofore have been so con` structed as to com rise a tube or casing, a

fuse strip, termina s for the same, a con-y ductor wire shunted across the said terminals and an indicating means electrically interposed between one end of the said conductor wire and one of the said terminals. In these safety fuses, the conductor wire has commonly been assed within the tube or casing from its sai connection with the indicating.

means and electrically connected at its other end to the other terminal, the function of the indicating means being to indicate the condition of the fuse strip and this indication is due not to the rupture of the said conductor wire but to the direct action of the current on the g said indicatin means. The conductor wire in these fuses 1s -therefore unprotected within the tube or casing and we have found by experiment, that in the blowing of the fuse strip, the point of rupture of the same belng approximately centrally thereof, that the current may be short circuited at the moment the fuse is ruptured through the conductor wire to the terminal at the non-indicating end of the fuse device. This is due to the resistance of the indicating connection and it will be manifest that when suchaction takes place, the indicating means being unaffected, does not perform its function and there is no way of 4ascertaining exteriorly strip 1s blown.

Now the obj ect of our presentinvention is the rovision of an inclosed safety fuse in whic the aforesaid short-circuiting of the conductor wire is impossible, .and in carrying out the same, we emplo a tube or casing, a fuse strip, terminals t erefor, an inclosed conductor within the casing and connected at one end to one of the said terminals, and an indicating means electrically inter osed between the other end of the said con uctor wire andthe other terminal,-as will be hereinafter more particularly described.

In the drawing, Figure l is a central longitudinal section of a safety fuse embodying our present invention. Fig. 2 is a section on line x, Fig. 1. Figs. 3, 5 and 7 are central longitudinal sections of fuse devices illustrating modifications of that form of the invention shown in Fig. 1. Fig. 4 is a cross section on line y, y, Fig. 3. Fig.6 is a cross section on line 2,2, Fig. 5. Fig. 8 is a crosssection on line x, a, Fig. 7, and Fig. 9 is a partial central longitudinal section of the safety fuse illustrating further modiiications of the in vention.

aJ designates a casing which, as is common in safety fuse devices, is preferably tubular and made of any good insulating material. The casing a is provided with end caps or terminals b, t', and within the casing we employ a fuse strip c which is electrically connected to the terminals b, b', by the fuse terminals d, d. The casing a, preferably adj acent to one end and in the outer surface thereof, is ,provided with a longitudinally disposed recess indicated at 2 and withinv .This conductor wire e is carried along the inner surface of the casing a, to a point below the resistance material S'Within the rece ss.2 and then through a suitable aperture in the casing a and has its other end embedded within the 'said resistance material 3. In this particular form of the invention, the terminal b is provided with an aperture indicated at 4 and the terminal b is so'placed on the casing a., that this aperture 4 comes immediately above the recess 2, which when the terminal l1 is placed in position is completely covered thereby, the aperture 4 being also filled with the resistance material 3 which is` caused to contact 'with thel said material in the recess 2, whereby this resistance material forms an indicating contact electrically interposed between one end of the said conductor wire and one of the said terminals and moreover is exteriorly visible at the aperture 4 to indicate the condition of the fuse strip. In this form of the invention we employ a lining f within the casing a and this lining f isreferably made of asbestos paper, but as W1 be readily understood, it may be made of insulating material 3 forming the indicating contact, and in this instance, the aperture 4 is placed adjacent to the edge of the terminal, and is also filled with insulating material 3, whereby the indicating contact is visible exteriorly of the terminal. h designates a strip of asbestos paper or plaster of paris or other similarly insulating material assed longitudinally along and secured to t e inner surface of the casing a and inclosing the said conductor wire e in order to prevent the same being short-circuited.

In Figs. 5 and 6, we have shown the casing a provided exteriorly with a longitudinal slit indicated at 6 and in this form of the invention the conductor wire e is connected at one end with the fuse terminal d at 7 and carried over the edge of the casing a, into\` and alone in the slit 6 to the recess 2 inthe other end of the casing, where the saine is embedded in the resistancematerial 3 forming the indicating contact electrically interposed between the terminal b and the said conductor wire e. In this instance, the recess is so placed in the easing a that when the terminal b is in position on the end thereof, the edge of the terminal will not coinpletely overlap said recess 2, whereby a portion of the resistance material 3 is visible exteriorly at the edge ofthe terminal t.

Figs. 7 and 8 illustrate a modification of the invention similar to that shown in Figs. 5' and 6, with the exception that in this instance, the casing is provided with an interior 'slit indicated at 8 and running longitudinally thereof. In this form, one end of the conductor wire e is electrically connected with the terminal. t", carried over the edge of the casing a and along in the slit 8 through an aperture in the casing e and into the recess 2 in the o posits end thereof, where the other end o' the said conductor wire e is embedded in the resistance magood electrical and heat I terial 3 forming the indicating means electrically interposed between the terminal l) and the conductor wire e and in this instance,

the'aperture 4 in the terminal b is located in` f casing a, placing therein the resistance material 3 forming the indicating contact as lin the other forms of the invention and employing two conductor wires e, one end of eachof which is connected to a terminal of the fuse device while the other end is embedded in the resistance material 3 and .the intermediate portions are protected against short circuiting the said conductor Wires 1n any of the manners hereinbefore described in the other forms of our invention. And it will be further understood that the indicating contact may be entirelyunder the ferrule or terminal and visible through the same, or partially under the ferrule and projecting beyond the edge thereof, and that in either of these constructions any of the hereinbefore described forms of protecting the conductor wire may be employed.

We claim as our invention:

1. A safety fuse comprising a one-compartment casing, a fuse stri terminals therefor, a conductor located etween the outer and inner surfaces of the casing, and means co-acting with the said conductor for visually indicating the condition of the fuse strip. v

2. A safety fuse comprising a one-compartment casing, a fuse stri terminals therefor, a conductor located between the outer and inner surfaces of the said casing and connected at one end with one of the said terminals and an indicating means electrically interposed between the other terminal and the other ed of the said conductor.

3. A safety fuse comprisin a 'tubular casing, a fuse strip, terminals t erefor, a conductor located completely Within the tube wall and connected at one end with one of said terminals, and an indicating means electrically interposed between the other terminal and the other end of said conductor.

4. A safety fuse comprising a tubular casing provided with a longitudinal slit in a surface thereof for its entire length, a fuse strip, terminals therefor, a conductor located in said longitudinal slit of the tubular casing and connected at one end to one of said terminals, and an indicating means electrically interposed between the other terminal and the other end of said conductor.

5; A safety fuse comprising a tubular casing O1-Wiese with a. v10l1gia1m-i Sia ai the surface thereof for its entire' length, a fuse tending throughv and visible strip, terminals therefor, a conductor located in said longitudinal slit of the tubular casing, and an indicating means co-acting with the said conductor. l

6. A safety fuse comprising a tubular casing, a fuse stri terminals, therefor, a conductor located Lfwetwe'en the outer and inner surfaces of thetubular casing, connected at one end with one of said terminals, and an indicating resistance connection electrically interposed between the other end of said conductor and the other terminal and exat the surface of the other terminal. v f f v 7. A safety fuse comprisin a tubular casing in the outer surface of `W `ch a recess is provided, a fuse strip, terminals therefor, a conductor located betweeny the outer and inner surfaces of the, tubular casing, and',

connected at one end with one of 4said ter minals, and at the other end entering said recess, and a resistance conducting material filling said recess in the casing and surroundend `extending tinto said recess, and a resistance conducting material iilhngsaid recess in the casing surrounding the free end of the conductor f located therein and electrically interposed between the other terminal and the body of the tubular casing and Which resistance conducting material is visible at' the latter terminal.

, Signed byl us this 6 day of lJul 1906.,

- GERALD W. T.

FRANK D. REYNOLDS.

`VVitnes'ses:

" R.\L. JAYNEs,

JOSEPH SAoHs.

` ing the free end of said conductor and visible -`with one of said terminals and at its other 

